


birthdays

by snyland



Category: Undertale (Video Game)
Genre: Alternate Universe - Humantale, Birthday Sex, F/M, Friends to Lovers, Smut
Language: English
Status: Completed
Published: 2017-09-24
Updated: 2017-09-24
Packaged: 2019-01-04 19:38:46
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,511
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12175329
Author URL: https://archiveofourown.org/users/snyland/pseuds/snyland
Summary: Sans snickers. “did you… forget you own birthday?” your blush only deepens and spreads across your face. He laughs.“S-Stop laughing, you jerk!” you exclaim.“oh-- oh my god, that’s hilarious.” he wheezes. “jeez, an’ithought i was lazy.”





	birthdays

**Author's Note:**

> HEY HEY IT'S MY BIRTHDAY Y'ALL
> 
> i have literally been working on this for...... a whole day. yeah. wow. 
> 
> SO THIS WAS GONNA BE A THING FOR THE ANIVERSARY AND MY BDAY BUT THAT DIDN'T HAPPENED i'll just do something for the aniversary..... later. 
> 
> read the bottom for my new tumblr & some humantale headcanons yo 
> 
> ALSO this was inspired by [this fanart](https://anarchypuppet.tumblr.com/post/165018267205/dig-dig-dig-dig-dig-and-burry-myself-remember) and the fic that goes with it.

Moonlight cuts through the curtains, a light breeze making it’s way through the barely open window and blowing them ever so slightly. 

 

Sans lies there, silently, watching you and your chest rises and falls, you breaths deep yet also soft. He has a soft look on his face as he watches you, his thumb stroking your cheek lovingly. 

 

He loves you. He knows it to be true; he known it for a while. He just… can’t bring himself to say it. You’ve quickly become his best friend in the world, and Sans has quickly found himself falling really, really hard for you. Harder than he thought himself capable, really-- who knew he of all people could fall in love so hard and so fast? 

 

Everytime you walk into the room, with your bright expression and light, carefree voice, he feels his heart instantly beat harder in his chest-- even more so when you embrace him, running your fingers through his hair the way you do, with him feeling the soft plushness of you fleshly hips in his arms. 

 

Everything about you, in his eyes, was perfect. Your eyes, your hair, your voice (god, your laugh never ceases to melt him into a puddle of mush), your smile, every little mannerism you have… he sees no flaws. He only only sees… you. 

 

Sans Aster is, without a doubt in his mind, head over heels in love with you. 

 

And, honestly? He doesn’t ever want to stop. 

 

Taking a long deep breath and scooting just a bit closer to you, Sans curls up in the blankets and falls asleep with a smile on his face. 

 

* * *

 

You wake up in the way you usually do. Slightly groggy and craving caffeine; your shirt has ridden up a bit in your sleep, same for the sweatpants you fell asleep in Sans’ room while binging some Netflix with him. The TV is off now, though-- seems Papyrus was in here. 

 

There is one difference than when you normally stay over the Aster Brother’s place-- you wake alone. Sans is nowhere to be seen, and judging from the distinct lack of noise in the house, it seems you’re alone in the house. 

 

You pull yourself from your best friends admittedly cozy blankets and yawn, slumping down the steps to the kitchen. You both loved and hated falling asleep in Sans’ bed-- it was super cozy, but also, it was  _ way _ too comfortable. No wonder he sleeps all the time. 

 

You walking into the kitchen, hearing soft sizzling sounds. Perhaps you weren’t so alone after all. 

 

You poke your head in-- Sans is leaning against the counter, typing away at his phone. Bacon and scrambled eggs sizzle in the pan, bread toasting in the toaster oven. His brows are knitted in deep concentration-- you can’t help but think how cute he is when makes faces like that. 

 

Okay, yes, you had fallen for your best friend. Was it cliche as hell? Yeah. Did you care a lot less than you should? Double yeah. Did you find yourself, on several occasions over the past few months, wanting to smooch his stupid, attractive face? Hell yeah. 

 

You sigh. He probably didn’t think of you like that. No, he definitely didn't think of you like that. Sans wasn’t the type to beat around the bush if he could help it. He was, usually, pretty upfront about most things. 

 

You friend lets out a breath, locking his screen and placing it on the counter. He goes to turn back to his cooking and his heterochromic eyes lock with yours. 

 

Sans’ eyes always tended to hypnotise you; his right iris was a deep chocolate brown, whereas his left was a light baby blue. It gave him his own charm, and went well with his caramel skin and hazel hair. 

 

“oh, uh,” he says, “g’mornin’, bud.” he gives you that charming, lop-sided smile he always does. You smile softly at him. “Hey.” 

 

“i was, uh, gonna surprise you with breakfast in bed this mornin’. woke up early and everything.” he says, turning back to the stove. “but uh… pap tried t’ help me cook and everything got burnt. then he and undyne went on the sunday jog.” though it seems his morning was rather eventful and stressful, Sans has nothing but a soft tone of pride in his voice. “man… someone oughta teach those two how to actually cook.” 

 

You giggle, walking up next to him, watching him fry the bacon and cook the eggs. “Yeah. But they have good intentions.” you say. 

 

Sans pauses, then he chuckles. “they sure do, buddy.” 

 

He gestures towards the table. “sit down, breakfast will be ready soon.” he says, “i’ll get ya coffee in a sec.” 

 

You nod, smiling at him. You walk over to the table and sit down, the otherwise comfortable silence invaded by the sound of sizzling bacon and the popping of grease. 

 

After a few moments of idle conversation, Sans places a plate and a mug of coffee in front of you. He made your eggs and bacon look like a smiley. 

 

You giggle. He was  _ such  _ a dork. You spare him a glance as he sits down with his own dish. He winks at you, that usual, trademarked smirk on his face. Your cheeks flush, and you look down at you food. You start eating, trying to drown out your thoughts of how cute he is and how much you wanna give him a kiss for doing this for you. 

 

The two of you eat in silence, though it’s not at all uncomfortable and actually kind of relaxing, until Sans breaks the silence. “...hey.” his voice is soft, almost timid. “happy birthday, y/n.”

 

You blink. It was…? 

 

Instantly you feel really dumb-- of course. Today was your birthday. No wonder he wanted to make you breakfast. Your cheeks flush pink-- oh god, this was embarrassing. 

 

Sans snickers. “did you… forget you own birthday?” your blush only deepens and spreads across your face. He laughs. 

 

“S-Stop laughing, you jerk!” you exclaim. 

 

“oh-- oh my god, that’s hilarious.” he wheezes. “jeez, an’ i thought i was lazy.” 

 

You pout at him. “It’s not that funny…” 

 

He laughs just a bit more, then leans his cheek on his palm. “heh heh, oh man.” he says, his expression relaxed. His eyes are half-lidded as he gazes at you. “god, you are so cute when you blush.” he says. 

 

Time, suddenly, feels like it’s standing still. It doesn’t take Sans any longer than two whole seconds to realize what it is he actually just said, and though he tries to keep a smile on his face, you can tell he did not mean to say that out loud. 

 

“uh--” he says, his eyes wide. “i-i, uh.” 

 

There’s more silence, though not  _ nearly  _ as comfortable as before. Suddenly, Sans stands so quickly he knocks his chair over onto the floor, making you jump.

 

“....i’m gonna. go jump in the shower.” he says. He turns and walks into his bedroom without another word, leaving you alone with a still steaming cup of coffee. 

* * *

 

It’s a few hours later and you were sitting with all your friends in Grillby’s. You were reasonably tipsy, as you’d been drinking a bit. Papyrus was the only sober one. Toriel, Undyne, Alphys and Mettaton were all mildly drunk, given as you’d only been there for about an hour and a half. 

Sans, on the other hand, was  _ completely wrecked. _

 

He was drunk within the first 30 minutes. The more he drank, the more non-family friendly his jokes got. Eventually you had to ask him to stop because he was making some other patrons uncomfortable. Lucky for you, he seemed to hang at your every word when he was drunk. Which was weird. 

 

He kept looking at you like some kind of love-struck puppy. Or at least in your general direction. You swear you hear Undyne tell Alphys that he may as have “freakin’ cartoon hearts coming out of his ears”. 

 

Eventually, Toriel has to leave. Her child (this really cute kid named Frisk, who apparently set your mage friends free from their underground prison) was getting to “that age” (read: they’re almost 12) and Toriel needed to keep an eye on them. 

 

Undyne and Alphys leave eventually too, claim they had some anime to catch up on. Mettaton leaves eventually, claiming he just “needed some air” and ends up dragging an idol-struck Papyrus out with him. 

 

And, once again, you were alone with Sans, who was only drinking more and more as time passed. 

 

After some careful prodding and some admittedly charming and almost flirtatious lines, Sans encourages you into trying one of Grillby’s magical drinks, and you instantly feel drunker.

 

“too intense?” he asks. 

 

“No, no,” you say, “it’s strong as hell and, wow that cinnamon is spicy, and I think I feel magic popping on my tounge but other than that this is… really good, actually.”

 

“...you wany another shot?” 

 

“Yes please!” 

 

So you and Sans do shots for 20 minutes. And then you’re both sloshed. Eventually Grillby has to close, so you have to go. 

 

You and Sans stumble out of Grillby’s and, after fumbling with your phone a bit and dropping it in a puddle, Sans suggests you go try another bar. With your phone damaged forever now, you sigh and relent. 

 

The two of you end up going bar hopping and you’re both too drunk to even stumble your way home so you end up dragging Sans to a motel for the night. 

As soon as you walk inside, you best friend in the world (and current crush) makes his way the bathroom to puke. You sigh. He shouldn’t have drank so much, the idiot. 

 

You lay in bed, clicking through channels. Eventually, after you make him wash out his mouth, Sans joins you. He sorta sits there for a while, slightly dazed. The eventually you feel his hand fall on yours. 

 

“...hey.” 

 

“...Yeah?” 

 

“i... y/n, i… should tell you something.” 

 

You heart starts beating faster. There was no way he was serious. No way. There was no way he…

 

“...heh. t’ be honest, i honestly and fully expect this to kinda… stonewall our friendship. at least for a while. which is fine. i’m chill with that.” he grips your hand like a lifeline. “...i really like you. like... really, really like you. and i would very much like to kiss you. right now. if that’s okay.”

 

Your brain was lagging. This can't be real, right? This was, obviously, a dream. You had just fallen asleep as soon as you hit the pillow. 

 

“...okay. Sure.” you say, turning toward him. 

 

Slowly, Sans looks at you. “...really?” 

 

You nod. “Really.” 

 

He wastes no time. Sans pounces on you in an instant, his lips attacking yours. He holds you flush to his broad chest, positioning you in his lap. The two of you end up making out, his tongue quickly taking dominance over yours. You whine and moan, completely giving in to him. He squeezes you thighs, letting out a sound that is nothing short of a growl. Distantly, you wonder when the last time he had sex, since he’s ravishing you like a starving man. 

 

“Sans…” you gasp, pulling back. “Sans, wait.” 

 

He pulls back, panting and looking at you with half-lidded eyes. “yes, my darling?” he says, giving you that same look again. 

 

You flush, remembering his words during breakfast. You suddenly can’t look right at him. “M-Maybe we should stop. We’re really drunk, and--” 

 

You’re suddenly cut off when Sans latches his mouth on your neck. He purrs, kissing and nibbling on your skin. You gasp in pleasure. You whine, feebly trying to stop him, but eventually giving in. Wow, he was good. 

 

Slowly, Sans slips his hands under your shirt. You grip his hair, the sharp tugs egging him on and leading him to unhook your bra and the next thing you’re aware of, you’re topless and he’s straddling you. 

 

He kisses his way down your neck, places kisses around your breasts, dragging his tongue down the valley between them. He licks, sucks and nibbles at one breast, the other being stimulated by his hand, which kneads and rolls your breast. The combined stimulation makes your mound wetter and wetter and you whine out his name. 

 

He pulls back, looking down at you. “do you want me to stop?” he pants. 

 

“N-No,” you gasp, “I need you Sans… I need all of you… please…” 

 

He smiles. “as you wish, my princess.” he says. He makes quick work of the clothes on your lower half, and then starts undressing himself. You take note of the scar on his chest, as if someone had taken a knife to his chest as hard as they could. You reach out to him and Sans is back on you in a second, his mouth ravaging yours, your hips bucking against each other. 

 

“god,” he shudders, “god, i love you.” his breath is labored as he drunkenly fumbles with your legs, wrapping them around his waist, positioning himself. 

 

He takes a breath, pulling back from the heated kiss and looking at you, “...ready?” You nod. Grunting, he slowly slips just the tip of his length inside you. “this okay?” he asks. 

 

“M...More… Saans~.” you moan. 

 

He lets out a soft purr, sliding himself further in slowly but steadily, watching your expression with half-lidded eyes. As he hilts himself, a shudder runs its way up your spine as he brushes against your sweet spot. 

 

Sans seems to notice, as his expression shifts slightly. He hums, but allows you a moment to get used to his girth. “...you good?” he asks eventually. 

 

You nod. “I’m all yours, Sans… please…” 

 

He looks at you a moment, then he chuckles. “as you wish.” 

 

He then starts a pace, thrusting into you again and again with abandon. He grips the headboard at one point to keep himself steady. He grunts and curses under his breath as he thrusts into you, your name but a whisper on his lips. 

 

“Nnngh, Sans… I’m getting close…” you whine. 

 

“ _fuck..._ you too, babydoll?” he asks. “nnn, fuck, fuuuuck… c-can i…”

 

You don’t even think when you respond, “Yes, Yes, Fuck, Sans please…” 

 

As if he was suddenly invigorated, Sans thrusts into you with vigor, praising you the whole time. He called you everything you could think of, from cut all the way to goddess. 

 

“ffffuck, y/n, baby, i’m gonna--” Then with one final thrust, orgasm hits you both like a truck. Sans whispers a string of curses under his breath, and you let out a whine of his name. 

 

Sans falls beside you, a smile of his face. He looks happy. 

 

You’re happy, too. 

 

Sans slips under the blankets, sighing softly. “c’mere.” he mutters. Curling up under the blankets, you oblige, resting your head on his chest. Sans sighs, instantly drifting off to sleep and wrapping his arms around you. 

 

You're starting to think this isn’t a dream anymore. 

**Author's Note:**

> wow that was 2000+ words of Self Indulgence yeesh.
> 
> [my new tumblr!](https://ellasrphub.tumblr.com/) NOW SOME HUMANTALE HEADCANONS 
> 
> \- instead of just being a species swap au, it's a fight between magical and non-magical humans \- they're called mages, witches, and wizards, depending on where you are in the world \- toriel is albino & she wears poofy dresses. \- sans, as mentioned in the fic, has hetrochromia. his left eye is blue with some yellow mixed in. his right is hazel, like papyrus. 
> 
> anyway it's almost 5 am & i gotta go to dinner for my birthday so i'll add more later lMAO


End file.
